Transient Kinetics of Short-Chain Perfluoroalkyl Sulfonate with Radiolytic Reducing Species

The role of the short-lived hydrated electron (eaq–) has recently begun to be appreciated in per- and polyfluoroalkyl substances (PFAS) remediations; nevertheless, few studies date focused on short-chain PFAS, their effective defluorination been limited by an insufficient mechanistic understanding, which starts with elusive initial step eaq– reduction. Herein, this study uses pulse radiolysis clarify rate constant reaction a highly recalcitrant perfluorobutanesulfonate (PFBS, C4F9SO3–), verify chain length dependence. measured values contradict earlier results from laser photolysis but reconcile apparent degradation profiles theoretical predictions. Besides, we first disclose radiolytic carbon dioxide radicals (CO2–•) defluorinate PFBS 4.8 × 107 M–1 s–1, it achieves selective cleavage more obstinate C–F bond than even under neutral condition. Quantitative 60Co γ-ray irradiation experiments further show that reduction occurs through pathway rather desulfurization pathway, redox potential exceeds −2.0 eV. This addressed long-standing contradictions regarding PFAS suggested ionizing radiation as versatile direct treatment technique.